1,648 research outputs found
Properties of cryogenically worked materials Final report
Steel and cobalt-nickel alloy compression and corrosion tests after precipitation hardening at cryogenic temperatures for increased yield strength and corrosion resistanc
Agent-Based Modeling and its Tradeoffs: An Introduction & Examples
Agent-based modeling is a computational dynamic modeling technique that may
be less familiar to some readers. Agent-based modeling seeks to understand the
behaviour of complex systems by situating agents in an environment and studying
the emergent outcomes of agent-agent and agent-environment interactions. In
comparison with compartmental models, agent-based models offer simpler, more
scalable and flexible representation of heterogeneity, the ability to capture
dynamic and static network and spatial context, and the ability to consider
history of individuals within the model. In contrast, compartmental models
offer faster development time with less programming required, lower
computational requirements that do not scale with population, and the option
for concise mathematical formulation with ordinary, delay or stochastic
differential equations supporting derivation of properties of the system
behaviour. In this chapter, basic characteristics of agent-based models are
introduced, advantages and disadvantages of agent-based models, as compared
with compartmental models, are discussed, and two example agent-based
infectious disease models are reviewed
Properties of cryogenically worked materials Interim report
Cryogenically worked materials during strain hardenin
How Christians Reconcile Their Personal Political Views and the Teachings of Their Faith: Projection as a Means of Dissonance Reduction
The present study explores the dramatic projection of one\u27s own views onto those of Jesus among conservative and liberal American Christians. In a large-scale survey, the relevant views that each group attributed to a contemporary Jesus differed almost as much as their own views. Despite such dissonance-reducing projection, however, conservatives acknowledged the relevant discrepancy with regard to fellowship issues (e.g., taxation to reduce economic inequality and treatment of immigrants) and liberals acknowledged the relevant discrepancy with regard to morality issues (e.g., abortion and gay marriage). However, conservatives also claimed that a contemporary Jesus would be even more conservative than themselves on the former issues whereas liberals claimed that Jesus would be even more liberal than themselves on the latter issues. Further reducing potential dissonance, liberal and conservative Christians differed markedly in the types of issues they claimed to be more central to their faith. A concluding discussion considers the relationship between individual motivational processes and more social processes that may underlie the present findings, as well as implications for contemporary social and political conflict
Metaphoric coherence: Distinguishing verbal metaphor from `anomaly\u27
Theories and computational models of metaphor comprehension generally circumvent the question of metaphor versus “anomaly” in favor of a treatment of metaphor versus literal language. Making the distinction between metaphoric and “anomalous” expressions is subject to wide variation in judgment, yet humans agree that some potentially metaphoric expressions are much more comprehensible than others. In the context of a program which interprets simple isolated sentences that are potential instances of cross‐modal and other verbal metaphor, I consider some possible coherence criteria which must be satisfied for an expression to be “conceivable” metaphorically. Metaphoric constraints on object nominals are represented as abstracted or extended along with the invariant structural components of the verb meaning in a metaphor. This approach distinguishes what is preserved in metaphoric extension from that which is “violated”, thus referring to both “similarity” and “dissimilarity” views of metaphor. The role and potential limits of represented abstracted properties and constraints is discussed as they relate to the recognition of incoherent semantic combinations and the rejection or adjustment of metaphoric interpretations
Double photo-ionization of He near a polarizable surface
We calculate the differential cross-section of the direct double
photo-ionization of He physisorbed on a polarizable surface. By including the
influence of the surface potential in the correlated two-electron final state
wavefunction, we show that the differential cross-section carries detailed
information on the electronic correlations at the surface. In particular,
photo-emission along opposite directions, which is prohibited in the free
space, is allowed if the surface potential is long-ranged.Comment: To appear in Phys. Rev. B - Rapid Comm. - 4 pages, 2 PostScript
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Lifetimes of image-potential states on copper surfaces
The lifetime of image states, which represent a key quantity to probe the
coupling of surface electronic states with the solid substrate, have been
recently determined for quantum numbers on Cu(100) by using
time-resolved two-photon photoemission in combination with the coherent
excitation of several states (U. H\"ofer et al, Science 277, 1480 (1997)). We
here report theoretical investigations of the lifetime of image states on
copper surfaces. We evaluate the lifetimes from the knowledge of the
self-energy of the excited quasiparticle, which we compute within the GW
approximation of many-body theory. Single-particle wave functions are obtained
by solving the Schr\"odinger equation with a realistic one-dimensional model
potential, and the screened interaction is evaluated in the random-phase
approximation (RPA). Our results are in good agreement with the experimentally
determined decay times.Comment: 4 pages, 1 figure, to appear in Phys. Rev. Let
Symbolic Software for the Painleve Test of Nonlinear Ordinary and Partial Differential Equations
The automation of the traditional Painleve test in Mathematica is discussed.
The package PainleveTest.m allows for the testing of polynomial systems of
ordinary and partial differential equations which may be parameterized by
arbitrary functions (or constants). Except where limited by memory, there is no
restriction on the number of independent or dependent variables. The package is
quite robust in determining all the possible dominant behaviors of the Laurent
series solutions of the differential equation. The omission of valid dominant
behaviors is a common problem in many implementations of the Painleve test, and
these omissions often lead to erroneous results. Finally, our package is
compared with the other available implementations of the Painleve test.Comment: Published in the Journal of Nonlinear Mathematical Physics
(http://www.sm.luth.se/math/JNMP/), vol. 13(1), pp. 90-110 (Feb. 2006). The
software can be downloaded at either http://www.douglasbaldwin.com or
http://www.mines.edu/fs_home/wherema
Self-energy of image states on copper surfaces
We report extensive calculations of the imaginary part of the electron
self-energy in the vicinity of the (100) and (111) surfaces of Cu. The
quasiparticle self-energy is computed by going beyond a free-electron
description of the metal surface, either within the GW approximation of
many-body theory or with inclusion, within the GW approximation, of
short-range exchange-correlation effects. Calculations of the decay rate of the
first three image states on Cu(100) and the first image state on Cu(111) are
also reported, and the impact of both band structure and many-body effects on
the electron relaxation process is discussed.Comment: 8 pages, 5 figures, to appear in Phys. Rev.
Zeta function determinant of the Laplace operator on the -dimensional ball
We present a direct approach for the calculation of functional determinants
of the Laplace operator on balls. Dirichlet and Robin boundary conditions are
considered. Using this approach, formulas for any value of the dimension, ,
of the ball, can be obtained quite easily. Explicit results are presented here
for dimensions and .Comment: 22 pages, one figure appended as uuencoded postscript fil
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